KR20110040389A - Preparation method of silk/hydroxyapatite hybrid nanofiber scaffold for bone regeneration - Google Patents

Abstract

PURPOSE: A manufacturing method of a silk/hydroxyapatite complex nanofiber supporter for osteanagenesis is provided to efficiently coat the silk nanofiber supporter with hydroxyapatite in a short time. CONSTITUTION: A manufacturing method of a silk/hydroxyapatite complex nanofiber supporter for osteanagenesis comprises: a step of preparing silk spinning undiluted solution; a step of electrospinning the silk spinning undiluted solution; a step of dispersing the spun silk nanofiber; a step of manufacturing silk nanofiber having a sponge shape by freeze-drying the dispersed silk nanofiber; a step of coating the silk nanofiber with hydroxyapatite by dipping the silk nanofiber in simulated body fluid; and a step of forming pores on the silk nanofiber coated with hydroxyapatite.

Description

Preparation method of silk / hydroxyapatite composite nanofiber support for bone regeneration {Preparation method of silk / hydroxyapatite hybrid nanofiber scaffold for bone regeneration}

The present invention relates to a method for producing silk / hydroxyapatite composite nanofiber support for bone regeneration.

Bone grafts are most common after blood transfusions, and are being performed in various areas to treat bone defects that are commonly seen in orthopedic surgery. According to reports, more than 500,000 bone grafts are performed annually in the United States, and around 2.2 million are performed annually worldwide. Bone grafts play a role in stimulating bone growth in areas where bone is missing due to pathological or physiological causes.

The action of bone grafts can be classified into osteoconduction, osteoinduction, and osteoogenesis depending on the mechanism. Bone conduction refers to the formation of bone by migrating osteoblasts from surrounding bone tissue to the bone graft site and mineral deposition, which only occurs when there is bone tissue or differentiated mesenchymal cells around. If bone conduction material is implanted in other sites, such as subcutaneous tissue, it will not initiate bone growth. When implanted into bone or soft tissue, the bone conduction material is absorbed and replaced with bone tissue through a process similar to the creeping substitution process. Osteoinduction is a process in which bone graft material induces undifferentiated mesenchymal cells and differentiates into bone precursor cells to form new bone tissue. Bone formation is also possible when transplanted into other tissues, such as subcutaneous tissue. Osteoinductive grafts also have a great impact on the process of remodeling. Osteoblasts refer to the generation of bone tissue by living cells in the graft and autologous bone is the only bone forming material.

Materials used for bone grafts include autologous bone, allogeneic bone, and xenograft. Recently, various artificial bone substitutes have been researched, developed, and used. Bone grafts should ideally meet the requirements of inducing bone formation, biocompatibility with the host, ease of collection and manipulation, and cost reduction, but currently used bone grafts have some limitations. have.

Autologous bone graft is the best material with all three characteristics of bone formation, bone induction and bone conduction for bone union, and shows better stability and transplantation rate than all other bone graft materials. However, there are drawbacks that can result in other defects, infections, and other complications in the donor involved in harvesting the graft, requiring additional surgery time, and often failing to obtain a sufficient amount of bone. In order to overcome this drawback, extensive research has been conducted to find a bone graft material to replace it.

Currently, the most commonly used allogeneic bone in place of autologous bone is tissue obtained from the same species as the host, and is provided in various forms such as particles, gels, putties, and the like by freezing, lyophilization, and decalcification drying. Allogeneic bone has a relatively large amount and has the advantage of controlling the shape or bone density by using a specific part of the skeleton or by processing. Allogeneic bone as an implant has excellent bone conduction, but bone cells do not survive, resulting in no bone formation and extremely limited bone induction. In addition, the supply is limited, there are restrictions such as ethical problems, there is a disadvantage that there is a risk of transmission or infection of contaminants, toxins and the like. In addition, allogeneic bone has the potential to transmit infectious diseases caused by viruses despite the thorough investigation of donors and various tests.To reduce this risk, allogeneic bone can be changed in its original biological and epidemiological properties. Because of this, there is a problem that can weaken the mechanical strength or adversely affect bone conductivity and bone induction.

Xenograft transplantation is limited to the processing of animal bones such as cows or pigs and implanted into the human body, but there is a problem such as the immune response and transmission of infectious diseases, the use is gradually decreasing.

Recently, due to the problems related to autologous bone, allogeneic bone, and xenograft, there is increasing interest in artificial bone substitutes that can provide biocompatibility and safety for bone graft, and many studies have been actively conducted.

Artificial bone substitutes are required to meet the following requirements. First, it should not cause infection and no or no antigen response, and second, it should be easy to handle without being broken during the procedure. Third, it should have good hygroscopicity in vivo. Fourth, sufficient mechanical strength to withstand the pressure of surrounding tissues after surgery. Fifth, to maintain a constant volume until bone tissue is sufficiently formed and mature in the support, sixth, to have a proper surface roughness to adhere well to the existing tissue, seventh, to adhere to the growth and differentiation of cells The nutrients or excreta should be porous enough to diffuse well. Eighth, additional products by decomposition of artificial bone substitutes should be biocompatible.

Currently, calcium phosphate-based compounds are in the spotlight as artificial bone materials. The most commonly used hydroxyapatite has the same structure as the main component of bones and teeth of the human body, and is used in the medical field by coating it on powder form, dense body or metal, and has excellent biocompatibility and biocompatibility. Since the bone conduction of the surrounding bone causes the development of artificial bone material, research and clinical applications are actively being conducted. However, in the case of the hydroxyapatite powder material, since the strength is low and it is difficult to use it as it is, research has been conducted on hybrid materials with organic materials to solve this problem.

Organic materials to hybridize with hydroxyapatite include biodegradable synthetic polymers such as polyglycolic acid (PGA), polylactic acid-glycolic acid copolymer (PLGA), polylactic acid (PLA), collagen, which is an organic component of bone, etc. Is used. However, biodegradable synthetic polymers such as polyglycolic acid, polylactic acid-glycolic acid copolymers, and polylactic acid have excellent structural stability and tensile strength, but are caused by the fact that the biodegradation period is longer than 2 years and the decomposition products are acidic substances. There are problems such as inflammatory reactions. In addition, since collagen has to be extracted from animals, it is difficult to manufacture and store, and it is not suitable for mass production, and thus the manufacturing cost is high, so it is limited for clinical use, the dissolution rate in the body is too fast, immune response and infectious disease It may cause, there is a problem that the tension is weak in vivo.

On the other hand, as the hydroxyapatite coating method, the plasma spraying method is most used, which is a method of melting the hydroxyapatite powder in the high temperature plasma region of 20,000 to 30,000 degrees and then fusion to the metal target. The coating layer coated by the plasma spraying method has a higher adhesion strength than the coating layer coated by chemical vapor deposition, sputtering, etc., but there is still a problem in that the destruction of the coating layer occurs on the metal surface and the surface of the coating layer. Recently, metal implants are deposited in a solution containing calcium and phosphate ions to precipitate hydroxyapatite on the metal surface, or the surface is modified and deposited in a simulated body fluid (SBF) to hydroxyapatite on the surface. Although a method of forming a layer and a method of coating apatite fine particles using electrophoresis have been developed, there is a problem in that deposition time is long when coating with hydroxyapatite using a human-like solution. Although there are examples of coating hydroxyapatite on fibers and the like, examples of application to silk nanofibers have not been reported so far, and particularly, even coatings of nanofiber surfaces are not reported.

Therefore, the present inventors have been studying to develop a bone graft material that can replace the existing artificial bone substitute, by using a human-like solution of 5 to 15 times the concentration in a short time without damaging the silk protein at room temperature and atmospheric pressure conditions. The present invention was completed by finding that hydroxyapatite can be efficiently coated on a silk nanofiber support without performing an additional process such as plasma treatment or surface treatment.

An object of the present invention is to provide a method for producing a silk / hydroxyapatite composite nanofiber support for bone regeneration.

In order to achieve the above object, the present invention comprises the steps of preparing a silk spinning stock solution (step 1); Electrospinning the silk spinning solution prepared in step 1 (step 2); Dispersing the silk nanofibers spun in step 2 (step 3); Preparing the silk nanofibers in the form of sponges three-dimensionally dispersed by freeze-drying the silk nanofibers dispersed in step 3 in a predetermined container (step 4); Step of immersing the silk nanofibers in the three-dimensional dispersed sponge form prepared in step 4 in a simulated body fluid (SBF) of 5 to 15 times the concentration of the composite coating with hydroxyapatite (step 5); And it provides a method for producing a silk / hydroxyapatite composite nanofiber support for bone regeneration comprising the step (step 6) to form a void in the silk nanofiber complex coated with hydroxyapatite in step 5.

The method for preparing silk / hydroxyapatite composite nanofiber support according to the present invention uses a human-like solution having a concentration of 5 to 15 times and additionally such as plasma treatment or surface treatment in a short time without damaging silk protein at room temperature and atmospheric pressure. The hydroxyapatite can be efficiently coated onto the silk nanofiber support without performing the process, and the crystallinity is lower than that of the hydroxyapatite, thereby preparing a silk / hydroxyapatite composite nanofiber support similar to natural bone.

The present invention provides a method for producing silk / hydroxyapatite composite nanofiber support for bone regeneration.

Hereinafter, the present invention will be described in detail.

Silk / hydroxyapatite composite nanofiber support according to the present invention

Preparing a silk spinning stock solution (step 1);

Electrospinning the silk spinning solution prepared in step 1 (step 2);

Dispersing the silk nanofibers spun in step 2 (step 3);

Preparing the silk nanofibers in the form of sponges three-dimensionally dispersed by freeze-drying the silk nanofibers dispersed in step 3 in a predetermined container (step 4);

Step of immersing the silk nanofibers in the three-dimensional dispersed sponge form prepared in step 4 in a simulated body fluid (SBF) of 5 to 15 times the concentration of the composite coating with hydroxyapatite (step 5); And

It can be prepared by the manufacturing method comprising the step (step 6) of forming a pore in the silk nanofiber complex coated with hydroxyapatite in step 5.

Hereinafter, the manufacturing method according to the present invention will be described in more detail step by step.

First, step 1 according to the present invention is a step of preparing a silk spinning stock solution.

The silk spinning stock solution is the step of removing sericin from the silk fibers (step a); Washing, drying and dialysis the silk fibers from which sericin has been removed to prepare an aqueous silk fibroin solution (step b); Freeze-drying the aqueous solution of silk fibroin to prepare a silk fibroin sponge (step c); And it can be prepared through the step of dissolving the silk fibroin sponge in a predetermined solvent and filtering (step d).

The silk fiber has a structure in which two strands of fibroin are wrapped in a sericin outer membrane, and since the fibroin has excellent biocompatibility and does not affect any surrounding tissues, it is manufactured in various forms such as powder, gel, and aqueous solution, and food. It can be used in various ways. When preparing the spinning stock solution using such silk fibers, it is preferable to remove sericin from the silk fibers in order to maximize biocompatibility. Sericin may be removed by immersing the silk nanofibers in a sodium oleate and sodium bicarbonate solution followed by heating.

Silk fibers from which the sericin is removed can be washed repeatedly with distilled water and dried, dissolved in a mixed solution of calcium chloride / water / ethanol, and then dialyzed with distilled water to prepare a silk fibroin aqueous solution. The dialysis membrane is preferably a dialysis membrane having a MWCO of 12 to 14 kDa.

The silk fibroin solution may be freeze-dried to prepare a silk fibroin sponge, and then dissolved in formic acid, followed by filtration to prepare a silk spinning stock solution.

In the silk spinning stock solution, it is preferable to prepare a solution having a concentration of 10 to 18% to smoothly perform the electrospinning process and to obtain nanofibers of uniform size and shape. Increasing the concentration within the concentration range of 10 to 18% increases the thickness of the fiber. If the concentration of the spinning stock solution is less than the above range, the viscosity of the spinning stock solution is too low to form fibers, and if it exceeds the range, the spinning stock solution may have high viscosity, which makes it difficult to form fibers by electric force, thereby stably electrospinning. No problem occurs.

Next, step 2 is a step of electrospinning the silk spinning stock prepared in step 1.

The electrospinning may be performed by using a predetermined radiator while applying a predetermined voltage. The electrospinning apparatus according to the present invention comprises a radiating part, a DC power supply part and a dispersing part. The spinning unit receives the spinning stock solution and serves to spin the received spinning stock solution into the nanofibers. When spinning the spinning solution in the spinning unit, it is preferable to keep the spinning speed constant, and therefore, it is preferable to use a syringe pump suitable for keeping the spinning speed constant. The DC power supply unit serves to apply a voltage during radiation, and is connected to the radiation unit. The dispersion part serves to disperse and solidify the spun fibers, and consists of a coagulation bath filled with coagulant liquid. The coagulation bath is made of a metal container and is grounded by a predetermined wire.

The voltage applied during the electrospinning is preferably set within the range of 10 to 15 kV because it can perform a stable spinning process. When the voltage increases within the voltage range of 10 to 15 kV, the spinning speed increases.

Next, step 3 is a step of dispersing the silk nanofibers spun in step 2, it can be made by dispersing the fibers spun in step 2 in a coagulation bath filled with a predetermined coagulant solution. Methanol may be used as the coagulating solution, but is not necessarily limited thereto.

Next, step 4 is to freeze-dried the silk nanofibers dispersed in the step 3 in a predetermined container to prepare silk nanofibers in the form of sponges dispersed in three dimensions.

In step 3, the fibers dispersed in the coagulation bath are nano-sized to have a gel-like state. Before performing freeze-drying, it is preferable to perform a process of removing the coagulation liquid present in the dispersed fibers. The coagulating solution can be removed by washing the fibers dispersed in the step 3 in distilled water. Freeze-drying is carried out in a state in which the fiber from which the coagulant has been removed is contained in a predetermined container, so that nanofibers in the form of sponges three-dimensionally dispersed in various shapes according to the shape of the container can be made.

Next, the step 5 is hydroxyapatite by immersing the three-dimensional dispersed sponge-type silk nanofibers prepared in step 4 in a simulated body fluid (SBF) of 5 to 15 times the concentration Complex coating step. The calcium / phosphorus (Ca / P) molar ratio of hydroxyapatite having Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ structure is 10/6, or 1.67, similar to human bone. The human bone is a structure in which the PO ₄ and OH groups are partially substituted with CO ₃ groups in the above structure, rather than pure hydroxyapatite.

Since the human-like solution is similar to the ionic composition of human plasma, when the porous biodegradable polymer support in which hydroxyapatite is formed is used, the hydroxyapatite is formed in the porous biodegradable polymer support by providing more environmental conditions. Can promote. In this case, the human body similar to the solution at a concentration of 10 times to 15 times is in 1ℓ of distilled water, _{^{Ca 2+ 2.5 mM, H 2 PO}} 4 2- including 1.0 mM, and ^{Na +, K +, Mg 2+} , Cl -, HCO ^3, relative to the human body similar to solution ^{(1 × SBF), Ca 2} + and H ^₂ PO _{4 2} for the reference solution containing the chemical species of the SO ₄ ^{2- -} 5-fold to 15-fold increase in the concentration of I mean. When the concentration of the human-like solution is less than five times, it may take a long time and hydroxyapatite may not be well coated on the surface of the silk nanofibers. When the concentration of the human-like solution is more than 15 times, silk The salt may precipitate in the solution before the hydroxyapatite is formed on the surface of the nanofibers, thereby preventing the hydroxyapatite coating. In high concentrations, there is a possibility of damaging the fiber structure by the salt solution.

The three-dimensionally dispersed sponge-shaped silk nanofibers prepared in step 4 were immersed in hydroxyapatite by immersing in a solution of human-like solution having a temperature of 37 ± 0.5 ° C. and a pH range of 7.2 to 7.4 for 30 minutes to 90 minutes. Can be coated. After the reaction is terminated, the remaining hydroxyapatite, which is not coated on the silk nanofibers, may be further washed with distilled water. If the washing is not done properly, unnecessary salt may remain, so washing with water is preferably performed three or more times.

Next, step 6 is a step of forming pores in the silk nanofibers coated with the hydroxyapatite complex in step 5.

The voids are dispersed in a dispersion medium of the silk nanofibers coated with the hydroxyapatite complex (step a); Adding particles for forming pores to the mixed solution (step b); Preparing a silk / hydroxyapatite composite nanofiber foam including the pore-forming particles using the mixture comprising the pore-forming particles obtained in step b (step c); And forming a pore-formed silk / hydroxyapatite composite nanofiber support by removing the pore-forming particles of the nanofiber foam (step d).

Step a is a step of dispersing the silk nanofiber complex coated with hydroxyapatite in a dispersion medium. The type of the dispersion medium is not particularly limited as long as it does not dissolve the pores forming particles and does not chemically and physically change the hydroxyapatite on the silk and the surface of the silk, but dioxane, carbon tetrachloride, trichloroethane, benzene, isopropanol , Cyclohexane, or a mixed solution thereof, and most preferably dioxane. The dioxane is an organic solvent suitable for freeze drying because it is frozen at 10 ° C. or lower and sublimation occurs at room temperature in a vacuum condition of 10 mTorr. It also does not dissolve silk fibroin and pore-forming particles, making it well suited for shaping and freeze-drying while maintaining the silk / hydroxyapatite composite nanofiber form.

The step b is a step of adding pore-forming particles to the mixed solution, the pore-forming particles are insoluble in the dispersion medium, and are removed by the steps described below, the type is not particularly limited, but sodium chloride, potassium chloride, calcium chloride , Sucrose, aluminum chloride and the like, and most preferably sodium chloride. The particle diameter of the pore-forming particles is preferably 100 to 200 μm, and it is preferable to use 0.01 to 0.02 g of pore-forming particles per 2 mg of silk nanofibers coated with hydroxyapatite.

Step c is a step of preparing a silk / hydroxyapatite composite nanofiber foam (foam) containing the pore-forming particles using the mixture containing the pore-forming particles obtained in step b. The silk / hydroxyapatite composite nanofiber foam may be prepared by freeze-drying the mixture including the pore-forming particles.

Step d is a step of forming the pores formed silk / hydroxyapatite composite nanofiber support by removing the particles for forming the pores of the nanofiber foam. The silk / hydroxyapatite composite nanofiber support is a solvent that solubilizes the pore-forming particles after vapor cross-linking the silk / hydroxyapatite composite nanofiber foam of step c using steam. It can be formed by immersing in, and performing the process of freeze drying the immersed silk / hydroxyapatite composite nanofiber foam. The use of the vapor crosslinking has the advantage that it is not necessary to wet the material to be crosslinked in the aqueous solution, so that the material vulnerable to moisture can be crosslinked. Here, the vapor is not particularly limited because it may vary depending on the nanofiber foam to be crosslinked, glutaraldehyde, carbodiimide, diphenylphosphoryl azide, ethyldimethylaminopropylcarbodiimide, toylene diisocyanate, hexamethylene It is preferable to use diisocyanate or the like. Subsequently, the vapor crosslinked nanofiber foam may be immersed in a solution in which the pore forming particles are soluble. At this time, it is preferable that the residual toxicity of the steam used in the steam crosslinking is removed. Subsequently, the immersed silk / hydroxyapatite composite nanofiber foam may be washed with a predetermined solvent and then lyophilized to prepare a nanofiber support according to the present invention.

According to the method for preparing the silk / hydroxyapatite composite nanofiber support according to the present invention, the hydroxyapatite may be treated without additional processes such as plasma treatment or surface treatment in a short time without damaging the silk protein at room temperature and atmospheric pressure. Can be coated.

Hereinafter, the present invention will be described in detail by way of examples, with the following examples being merely illustrative of the present invention, and the content of the present invention is not limited by the following examples.

< Example  1> silk Of Hydroxyapatite  Preparation of composite nanofiber supports 1

Step 1: silk  Preparation of Spinning Solution

The dried gamma cocoons were immersed in a bath ratio of 1:25 in 0.3% soap and 0.2% sodium bicarbonate solution and treated at 100 ° C. for 1 hour to remove sericin protein. The cocoons from which sericin was removed were repeatedly washed with distilled water and dried, and then dissolved in a solution of calcium chloride / water / ethanol in a molar ratio of 1: 8: 2 at 85 ° C. for 3 minutes in a bath ratio of 1:25. The dissolved solution was dialyzed for 3 days using a dialysis membrane to prepare an aqueous silk fibroin solution. The silk fibroin aqueous solution was freeze-dried to prepare a silk fibroin sponge, which was dissolved in 98% formic acid at a concentration of 12% and the insolubles were filtered to prepare a silk spinning stock solution.

Step 2: silk  Electrospinning of Radiant Solution

The spinning solution prepared in step 1 was performed using an electrospinning apparatus as described above. In more detail with respect to the electrospinning apparatus, a syringe pump including a 22 G injection needle was used as the spinning unit, and the distance between the spinning unit and the coagulation bath was set to about 15 cm and 10 kV. Electrospinning was performed with an applied voltage.

Step 3: Dispersion of Spun Silk Nanofibers

As a coagulation bath of the nanofibers prepared in step 2, methanol was used. After performing the electrospinning process, the nanofibers dispersed in the coagulation bath were put in a dialysis membrane and dialyzed with distilled water for 2 days to remove methanol used as the coagulation bath.

Step 4: Lyophilization

Silk fibroin nanofibers from which methanol was removed in step 3 was lyophilized in an appropriate container to obtain silk nanofibers in the form of sponge.

Step 5: With hydroxyapatite  Composite coated silk  Preparation of Nanofibers

NaCl 58.430 g, KCl 0.373 g, CaCl ₂ 3.675 g, MgCl ₂ 1.016 g, NaH ₂ PO ₄ 1.420 g, NaHCO ₃ 0.840 g in 1 L distilled water in 10-fold concentration (10 × SBF solution) ) Was prepared. Here, the silk nanofibers were immersed at a rate of 50 ml of the human-like solution having a 10-fold concentration per 10 mg of the silk nanofibers obtained in step 4, and then immersed at 37 ° C. for 30 minutes to be coated with hydroxyapatite. After the reaction, the silk nanofibers were washed three times with distilled water and then lyophilized to obtain silk nanofibers in the form of sponges coated with hydroxyapatite.

Step 6: Voids  Formed silk Of Hydroxyapatite  Preparation of Composite Nanofiber Supports

The silk nanofibers coated with the hydroxyapatite obtained in step 5 were coated in dioxane and allowed to stand for 12 hours to be sufficiently dispersed. Thereafter, sodium chloride having an average particle diameter of 100 to 200 µm was added to disperse the mixed well with the silk nanofibers coated with the hydroxyapatite, and then filled into a glass tube having an inner diameter of 6 mm, and then freeze-dried to give silk / A hydroxyapatite composite nanofiber foam was prepared. The silk / hydroxyapatite composite nanofiber foam was placed in a desiccator saturated with glutaaldehyde vapor and treated for 24 hours to allow crosslinking between the silk fibroin molecular chains. After crosslinking treatment, the mixture was immersed in an aqueous 0.1 M glycine solution and stirred while being exchanged at 6 hour intervals for 24 hours. Upon stirring, the desired pores were formed in the support while the sodium chloride particles melted. Then, washed three times with PBS (phosphate buffer saline) again, soaked and stirred for 24 hours, and through the process of freeze-drying to obtain a silk / hydroxyapatite composite nanofiber support having a porous structure.

< Example  2> silk Of Hydroxyapatite  Preparation of Composite Nanofiber Supports 2

Silk / hydroxyapatite composite nanofiber support having a porous structure in the same manner as in Example 1, except that the reaction was performed for 60 minutes by immersing in a human-like solution having a 10-fold concentration in Example 5 of Example 1. Obtained.

Example 3 Preparation of Silk / Hydroxyapatite Composite Nanofiber Support 3

In the same manner as in Example 1, except for reacting for 90 minutes by immersing in a human-like solution of 10 times the concentration in Example 5, the silk / hydroxyapatite composite nanofiber support having a porous structure Obtained.

< Example  4> silk Of Hydroxyapatite  Preparation of Composite Nanofiber Supports 4

In the same manner as in Example 1, except for immersing in a human-like solution of 10 times concentration in step 5 of Example 1 and reacting for 120 minutes, the silk / hydroxyapatite composite nanofiber support having a porous structure Obtained.

Example 5 Preparation of Silk / Hydroxyapatite Composite Nanofiber Support 5

Silk / hydroxyapatite composite nanofiber support having a porous structure in the same manner as in Example 1, except that the reaction was performed for 60 minutes by immersing in a human-like solution having a concentration of 5 times in Example 5 of Example 1. Obtained.

< Example  6> silk Of Hydroxyapatite  Preparation of Composite Nanofiber Supports 6

Silk / hydroxyapatite composite nanofiber support having a porous structure in the same manner as in Example 1, except that the reaction was carried out for 60 minutes by immersing in a human-like solution having a 15-fold concentration in Example 5 of Example 1. Obtained.

< Example  7> silk Of Hydroxyapatite  Preparation of Composite Nanofiber Supports 7

Silk / hydroxyapatite composite nanofiber support having a porous structure in the same manner as in Example 1, except that the reaction was carried out for 60 minutes by immersing in a 20 times human-like solution in step 5 of Example 1. Obtained.

< Comparative example  1> 1.5 times concentration Human body  Solution silk Of Hydroxyapatite  Preparation of Composite Nanofiber Supports

The porous structure was performed in the same manner as in Example 1, except that in step 5 of Example 1, the reaction was performed for 1 week using the human-like solution of 1.5-fold concentration instead of the 10-fold human-like solution. Silk / hydroxyapatite composite nanofiber support was obtained.

< Comparative example  2> silk  Preparation of Nanofiber Supports

A silk nanofiber support was obtained in the same manner as in Example 1, except that Step 5 of Example 1 was not performed.

< Experimental Example  1> according to the concentration of the solution Hydroxyapatite  Coating thickness change measurement

The following experiment was performed to determine the hydroxyapatite coating thickness change according to the concentration of the human-like solution of the silk / hydroxyapatite composite nanofiber support according to the present invention.

The scanning transfer microscope image of Comparative Example 1 is shown in Figure 1 (a), the scanning transfer microscope image of Example 5 is shown in Figure 1 (b), the scanning transfer microscope image of Example 2 1 (c), the scanning transfer microscope image of Example 6 is shown in Figure 1 (d), the scanning transfer microscope image of Example 7 is shown in Figure 1 (e). In addition, X-ray powder diffraction (X-ray Diffraction, XRD) spectra of Comparative Examples 2 and 2 are shown in FIG. 2.

As shown in (a) of FIG. 1, in the silk / hydroxyapatite composite nanofiber support of Comparative Example 1 according to the present invention, it can be seen that hydroxyapatite is formed on the surface of the silk nanofiber in the form of granules. In addition, as shown in (b), (c) and (d) of Figure 1, the silk / hydroxyapatite composite nanofiber support according to the present invention is coated with a large amount of hydroxyapatite as the concentration of the human-like solution increases It can be seen that this is done. However, as shown in (e) of FIG. 1, in Example 7, according to the present invention, before the hydroxyapatite is formed on the surface of the silk nanofibers, the salt is precipitated in the solution to prevent the hydroxyapatite coating. It can be seen that.

As shown in FIG. 2, the silk / hydroxyapatite composite nanofiber support of Example 2 according to the present invention has diffraction peaks corresponding to crystal lattice planes ((002) and (211)) showing hydroxyapatite inorganic crystal structures. Can be seen at 26 ° and 32 °, respectively.

Thus, the method for preparing the silk / hydroxyapatite composite nanofiber support according to the present invention uses a human-like solution having a concentration of 5 to 15 times the plasma treatment or surface treatment in a short time without damaging the silk protein at room temperature and atmospheric pressure conditions. It can be seen that hydroxyapatite can be efficiently coated on the silk nanofiber support without such an additional process.

< Experimental Example  2> human body similar solution Immersion  Over time Hydroxyapatite  Coating thickness change measurement

The following experiment was carried out to determine the hydroxyapatite coating thickness change according to the immersion time in the human-like solution of the silk / hydroxyapatite composite nanofiber support according to the present invention.

The mass change and average fiber diameter of Examples 1 to 4 were measured, and the results are shown in Table 1 and FIG. 3.

division % Change in mass Average fiber thickness (nm) Example 1 124.6 ± 15.66 428.7 ± 54.40 Example 2 130.9 ± 21.59 538.7 ± 81.73 Example 3 150.7 ± 20.32 1207.47 ± 140.29 Example 4 176.4 ± 25.48 Not measurable

Referring to Table 1, it can be seen that in Examples 1 to 4, the mass and the average fiber thickness increase as the immersion time in the human-like solution increases. In particular, in the case of Example 4, it can be seen that the thickness of the fiber is too thick to measure the fiber thickness.

As shown in (a) of FIG. 3, the silk / hydroxyapatite composite nanofiber support of Example 1 according to the present invention has a hydroxyapatite coating which does not cover the entire silk nanofiber evenly and partially on the fiber surface like granules. You can see that it was born. As shown in (b) of FIG. 3, the silk / hydroxyapatite composite nanofiber support of Example 2 according to the present invention can be seen that the hydroxyapatite coating covers almost all of the silk nanofibers. As shown in (c) of FIG. 3, the silk / hydroxyapatite composite nanofiber support of Example 3 according to the present invention is not only the hydroxyapatite coating completely covers the surface of the silk nanofiber, but also maintains the shape of the fiber. I can see that there is. As shown in (d) of FIG. 3, the silk / hydroxyapatite composite nanofiber support of Example 4 according to the present invention can be seen that the hydroxyapatite coating is thickened to lose the form of silk nanofibers and have changed to almost planar shape. have.

In addition, FT-IR spectra of Examples 1 to 4 and Comparative Example 2 are shown in FIG. 4. As shown in FIG. 4, it can be seen that in the method for preparing the silk / hydroxyapatite composite nanofiber support according to the present invention, the peak representing the P-O bond of the hydroxyapatite increases as the immersion time in the human-like solution increases.

Through this, it can be seen that the manufacturing method of the silk / hydroxyapatite composite nanofiber support according to the present invention can control the thickness of the hydroxyapatite coating by controlling the immersion time in the human-like solution.

< Experimental Example  3> Human body  solution Immersion  Generated through Hydroxyapatite  Elemental Analysis of Coatings

The following experiment was performed to determine the element content of the hydroxyapatite coating produced by immersion of the human-like solution of the silk / hydroxyapatite composite nanofiber support according to the present invention.

Elemental analysis (Energy Dispersive Spectroscopy, EDS) results of Example 2 are shown in FIG. As shown in Figure 5, the silk / hydroxyapatite composite nanofiber support of Example 2 according to the present invention can be seen that the ratio of Ca ions and P ions of hydroxyapatite is 1.61. In the case of hydroxyapatite (Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ), the ratio of Ca ions and P ions is generally 1.67. It is common to add less and have a ratio of Ca to P less than 1.67.

Therefore, the method for preparing the silk / hydroxyapatite composite nanofiber support according to the present invention uses a human-like solution having a concentration of 5 to 15 times, such as plasma treatment or surface treatment in a short time without damaging the silk protein at room temperature and atmospheric pressure. The hydroxyapatite can be efficiently coated on the silk nanofiber support without performing an additional process, and the silk / hydroxyapatite composite nanofiber support similar to the natural bone can be prepared with low crystallinity compared to the hydroxyapatite.

1 is a scanning electron microscopy image of the silk / hydroxyapatite composite nanofiber support for the concentration change of the human-like solution according to the present invention ((a) Comparative Example 1, (b) Example 5, (c) Example 2, (d) Example 6, (e) Example 7);

Figure 2 is a graph showing the X-ray powder diffraction (X-ray Diffraction, XRD) spectrum of the silk / hydroxyapatite composite nanofiber support according to the present invention;

3 is a scanning electron microscope image of the silk / hydroxyapatite composite nanofiber support according to the immersion time in the concentration of the human-like solution according to the present invention ((a) Example 1, (b) Example 2, (c Example 3, (d) Example 4);

4 is a FT-IR spectrum measurement results of the silk / hydroxyapatite composite nanofiber support according to the immersion time in the concentration of the human-like solution according to the present invention; And

5 is an EDS spectrum measurement result of analyzing the element content of hydroxyapatite produced by the human-like solution according to the present invention.

Claims (16)

Preparing a silk spinning stock solution (step 1); Electrospinning the silk spinning solution prepared in step 1 (step 2); Dispersing the silk nanofibers spun in step 2 (step 3); Preparing the silk nanofibers in the form of sponges three-dimensionally dispersed by freeze-drying the silk nanofibers dispersed in step 3 in a predetermined container (step 4); Step of immersing the silk nanofibers in the three-dimensional dispersed sponge form prepared in step 4 in a simulated body fluid (SBF) of 5 to 15 times the concentration of the composite coating with hydroxyapatite (step 5); And Method for producing a bone / silk hydroxyapatite composite nanofiber support for bone regeneration comprising the step (step 6) of forming a pore in the silk nanofiber complex coated with hydroxyapatite in step 5. (In humans similar solution of a concentration of 10 times to 15 times in the above step 5 is in 1ℓ of distilled water, _{^{Ca 2+ 2.5 mM, H 2 PO}} 4 2- including 1.0 mM, and ^{Na +, K +, Mg 2+} , Cl ^-, HCO ^3-, based on the human body similar to the solution containing the chemical species of the SO ₄ ^2-, and (1 × SBF), to 5 times the concentration of Ca ²⁺ and H ₂ PO ₄ ^2- on the reference solution Increased by 15 times). According to claim 1, wherein the silk spinning stock solution of step 1 Removing sericin from the silk fibers (step a); Washing, drying and dialysis the silk fibers from which sericin has been removed to prepare an aqueous silk fibroin solution (step b); Freeze-drying the aqueous solution of silk fibroin to prepare a silk fibroin sponge (step c); And And dissolving the silk fibroin sponge in a predetermined solvent, followed by filtration (step d). The method of preparing a silk / hydroxyapatite composite nanofiber support for bone regeneration. The method of claim 2, wherein the silk spinning stock solution is prepared in a concentration of 10 to 18% of the method for producing a silk / hydroxyapatite composite nanofiber support for bone regeneration. The method of claim 1, wherein the electrospinning of step 2 is applied to the voltage in the voltage range of 10 to 15 kV bone regeneration silk / hydroxyapatite composite nanofiber support. The method of claim 1, wherein the dispersion of step 3 of the silk regenerated silk / hydroxyapatite composite nanofiber support for bone regeneration characterized in that the dispersion in the coagulation bath filled with a predetermined coagulation solution Manufacturing method. The method of claim 1, wherein the three-dimensionally dispersed sponge nanofibers of step 5 are immersed in a human-like solution having a temperature of 37 ± 0.5 ° C. and a pH range of 7.2 to 7.4 for 30 minutes to 90 minutes. Method for producing a silk / hydroxyapatite composite nanofiber support for bone regeneration. The method of claim 1, wherein the pores of step 6 Dispersing the composite coated silk nanofibers with hydroxyapatite in a dispersion medium (step a); Adding particles for forming pores to the mixed solution (step b); Preparing a silk / hydroxyapatite composite nanofiber foam including the pore-forming particles using the mixture comprising the pore-forming particles obtained in step b (step c); And Silk / hydroxyapatite composite for bone regeneration, characterized in that it comprises a step (step d) of forming a nano-fiber support for forming a pore formed silk / hydroxyapatite composite by removing the particles for forming the pore of the nanofiber foam Method for producing a nanofiber support. The silk for bone regeneration according to claim 7, wherein the dispersion medium of step a is any one selected from the group consisting of dioxane, carbon tetrachloride, trichloroethane, benzene, isopropanol, cyclohexane, or a mixed solution thereof. Method for producing / hydroxyapatite composite nanofiber support. The method of claim 7, wherein the pore-forming particles of step b is any one selected from the group consisting of sodium chloride, potassium chloride, calcium chloride, sucrose and aluminum chloride silk / hydroxyapatite composite for bone regeneration Method for producing a nanofiber support. According to claim 7, wherein the particle diameter of the pore-forming particles of step b is a method for producing a bone / silk hydroxyapatite composite nanofiber support for bone regeneration, characterized in that. The method of claim 7, wherein 0.01 to 0.02 g of pore-forming particles are used per 2 mg of the silk nanofiber coated with the hydroxyapatite. . The method of claim 7, wherein the silk / hydroxyapatite composite nanofiber foam of step c is prepared by lyophilizing the mixture comprising the pore-forming particles obtained in the step b silk / hydroxy for bone regeneration Method for producing apatite composite nanofiber support. The method of claim 7, wherein the silk / hydroxyapatite composite nanofiber support of step d is subjected to vapor cross-linking (vapor) of the silk / hydroxyapatite composite nanofiber foam of the step c, Method for producing a bone / silk hydroxyapatite composite nanofiber support for bone regeneration characterized in that it is formed by immersing in the solvent solubilizing the pore-forming particles, the freeze-dried silk / hydroxyapatite composite nanofiber foam. . The method of claim 13, wherein the vapor is any one selected from the group consisting of glutaraldehyde, carbodiimide, diphenylphosphoryl azide, ethyldimethylaminopropylcarbodiimide, toylene diisocyanate and hexamethylene diisocyanate Method for producing a silk / hydroxyapatite composite nanofiber support for bone regeneration. The method of claim 1, wherein the silk nanofibers are coated with hydroxyapatite in a short time without damaging the silk protein at room temperature and atmospheric pressure. The method of claim 1, wherein the silk nanofibers are coated with hydroxyapatite without performing an additional process such as plasma treatment or surface treatment.

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